近100个C语言基础算法案例（初级篇）

本文是该系列的第一篇，都是一些相对初级的算法，很适合刚开始学C语言的同学。

1、C语言打印一条语句

源代码：

/* C Program to print a sentence. */
#include <stdio.h>
int main()
{
   printf("C Programming"); /* printf() prints the content inside quotation */
   return 0;
}

输出：

C Programming

2、C语言打印用户输入的一个整数

源代码：

#include <stdio.h>
int main()
{
    int num;
    printf("Enter a integer: ");  
    scanf("%d",&num);  /* Storing a integer entered by user in variable num */
    printf("You entered: %d",num);
    return 0;
}

输出：

Enter a integer: 25
You entered: 25

3、C语言实现两个整数相加

源代码：

/*C programming source code to add and display the sum of two integers entered by user */

#include <stdio.h>
int main( )
{
    int num1, num2, sum;
    printf("Enter two integers: ");
    scanf("%d %d",&num1,&num2); /* Stores the two integer entered by user in variable num1 and num2 */

    sum=num1+num2;      /* Performs addition and stores it in variable sum */
    printf("Sum: %d",sum);  /* Displays sum */
    return 0;
}

输出：

Enter two integers: 12
11
Sum: 23

4、C语言实现两个小数相乘

源代码：

/*C program to multiply and display the product of two floating point numbers entered by user. */

#include <stdio.h>
int main( )
{
    float num1, num2, product;
    printf("Enter two numbers: ");
    scanf("%f %f",&num1,&num2);        /* Stores the two floating point numbers entered by user in variable num1 and num2 respectively */
    product = num1*num2;  /* Performs multiplication and stores it */
    printf("Product: %f",product);
    return 0;
}

输出：

Enter two numbers: 2.4
1.1
Product: 2.640000

5、C语言查找字符的ASCII值

源代码：

/* Source code to find ASCII value of a character entered by user */

#include <stdio.h>
int main(){
    char c;
    printf("Enter a character: ");
    scanf("%c",&c);        /* Takes a character from user */
    printf("ASCII value of %c = %d",c,c);
    return 0;
}

输出：

Enter a character: G
ASCII value of G = 71

6、C语言根据用户输入的整数做商和余数

源代码：

/* C Program to compute remainder and quotient  */

#include <stdio.h>
int main(){
    int dividend, divisor, quotient, remainder;
    printf("Enter dividend: ");
    scanf("%d",&dividend);
    printf("Enter divisor: ");
    scanf("%d",&divisor);
    quotient=dividend/divisor;           /*  Computes quotient */
    remainder=dividend%divisor;          /* Computes remainder */
    printf("Quotient = %d\n",quotient);
    printf("Remainder = %d",remainder);
    return 0;
}

输出：

Enter dividend: 25
Enter divisor: 4
Quotient = 6
Remainder = 1

7、C语言获取整型、单精度浮点型、双精度浮点型和字符型的长度

基本语法是：

temp = sizeof(operand);
/* Here, temp is a variable of type integer,i.e, sizeof() operator 
   returns integer value. */

源代码：

/* This program computes the size of variable using sizeof operator.*/

#include <stdio.h>
int main(){
    int a;
    float b;
    double c;
    char d;
    printf("Size of int: %d bytes\n",sizeof(a));
    printf("Size of float: %d bytes\n",sizeof(b));
    printf("Size of double: %d bytes\n",sizeof(c));
    printf("Size of char: %d byte\n",sizeof(d));
    return 0;
}

输出：

Size of int: 4 bytes
Size of float: 4 bytes
Size of double: 8 bytes
Size of char: 1 byte

注：可能会由于系统的不同出来的结果也不尽相同。

8、C语言获取关键字long的长度范围

源代码：

#include <stdio.h>
int main(){
    int a;
    long int b;                /* int is optional. */
    long long int c;            /* int is optional. */
    printf("Size of int = %d bytes\n",sizeof(a));
    printf("Size of long int = %ld bytes\n",sizeof(b));
    printf("Size of long long int = %ld bytes",sizeof(c));
    return 0;
}

输出：

Size of int = 4 bytes
Size of long int = 4 bytes
Size of long long int = 8 bytes

9、C语言交换数值

源代码：

#include <stdio.h>
int main(){
      float a, b, temp;
      printf("Enter value of a: ");
      scanf("%f",&a);
      printf("Enter value of b: ");
      scanf("%f",&b);
      temp = a;    /* Value of a is stored in variable temp */
      a = b;       /* Value of b is stored in variable a */
      b = temp;    /* Value of temp(which contains initial value of a) is stored in variable b*/
      printf("\nAfter swapping, value of a = %.2f\n", a);
      printf("After swapping, value of b = %.2f", b);
      return 0;
}

输出：

Enter value of a: 1.20
Enter value of b: 2.45

After swapping, value of a = 2.45
After swapping, value of b = 1.2

10、C语言检查数值是奇数还是偶数

源代码：

/*C program to check whether a number entered by user is even or odd. */

#include <stdio.h>
int main(){
      int num;
      printf("Enter an integer you want to check: ");
      scanf("%d",&num);
      if((num%2)==0)      /* Checking whether remainder is 0 or not. */
           printf("%d is even.",num);
      else
           printf("%d is odd.",num);
      return 0;
}

输出1：

Enter an integer you want to check: 25
25 is odd.

输出2：

Enter an integer you want to check: 12
12 is even.

也可以用条件运算符解决：

/* C program to check whether an integer is odd or even using conditional operator */

#include <stdio.h>
int main(){
    int num;
    printf("Enter an integer you want to check: ");
    scanf("%d",&num);
    ((num%2)==0)   printf("%d is even.",num) : printf("%d is odd.",num);
    return 0;
}

11、C语言检查是元音还是辅音

源代码：

#include <stdio.h>
int main(){
  char c;
  printf("Enter an alphabet: ");
  scanf("%c",&c);
  if(c=='a'||c=='A'||c=='e'||c=='E'||c=='i'||c=='I'||c=='o'||c=='O'||c=='u'||c=='U')
       printf("%c is a vowel.",c);
  else
       printf("%c is a consonant.",c);
  return 0;
}

输出1：

Enter an alphabet: i
i is a vowel.

输出2：

Enter an alphabet: G
G is a consonant.

也可以用条件运算符解决

/* C program to check whether a character is vowel or consonant using conditional operator */

#include <stdio.h>
int main(){
 char c;
 printf("Enter an alphabet: ");
 scanf("%c",&c);
 (c=='a'||c=='A'||c=='e'||c=='E'||c=='i'||c=='I'||c=='o'||c=='O'||c=='u'||c=='U')   printf("%c is a vowel.",c) : printf("%c is a consonant.",c);
  return 0;
}

输出结果和上面的程序相同。

12、C语言实现从三个数值中查找最大值

实现1：

/* C program to find largest number using if statement only */

#include <stdio.h>
int main(){
      float a, b, c;
      printf("Enter three numbers: ");
      scanf("%f %f %f", &a, &b, &c);
      if(a>=b && a>=c)
         printf("Largest number = %.2f", a);
      if(b>=a && b>=c)
         printf("Largest number = %.2f", b);
      if(c>=a && c>=b)
         printf("Largest number = %.2f", c);
      return 0;
}

实现2：

/* C program to find largest number using if...else statement */

#include <stdio.h>
int main(){
      float a, b, c;
      printf("Enter three numbers: ");
      scanf("%f %f %f", &a, &b, &c);
      if (a>=b)
      {
          if(a>=c)
            printf("Largest number = %.2f",a);
          else
            printf("Largest number = %.2f",c);
      }
      else
      {
          if(b>=c)
            printf("Largest number = %.2f",b);
          else
            printf("Largest number = %.2f",c);
      }
      return 0;
}

实现3：

/* C Program to find largest number using nested if...else statement */

#include <stdio.h>
int main(){
      float a, b, c;
      printf("Enter three numbers: ");
      scanf("%f %f %f", &a, &b, &c);
      if(a>=b && a>=c)
         printf("Largest number = %.2f", a);
      else if(b>=a && b>=c)
         printf("Largest number = %.2f", b);
      else
         printf("Largest number = %.2f", c);
      return 0;
}

输出结果相同：

Enter three numbers: 12.2
13.452
10.193
Largest number = 13.45